Hitherto, as a technology of forming a thin film having gas barrier properties (hereinafter, also referred to as a gas barrier thin film in some cases), a heat generation element CVD method is known. The heat generation element CVD method is also called a Cat-CVD method or a hot wire CVD method and is a method of decomposing a raw material gas by bringing the raw material gas into contact with a heat generation element that has been caused to generate heat, and depositing the chemical species thus produced as a thin film on a surface of a plastic molded body directly or after a reaction process in a gas phase (for example, see Patent Literature 1).